This study aimed to evaluate the fermentation profile, nutritional quality, microbial count, fermentation losses, and aerobic stability of corn silages at different stages of maturity that were treated with organic acids (OA; Mold-Zap, Alltech, Nicholasville, KY). The OA (8 g kg-1 DM) was applied to corn silage harvested at the early, medium, or late stage, before compaction in the bunk. Lactic acid decreased with silage maturity (P<0.01). Compared to the control, the OA-treated silage had higher lactic acid content in the early-maturity silage (90.0 vs. 51.7 g kg-1 DM), but lower lactic acid in [1]the late-maturity silage (33.7 vs. 51.6 g kg-1 DM). Both early- and late-maturity silages with OA had lower yeast counts and DM losses (P<0.01). Silage heating upon air exposure was also lower in late-maturity silage with OA (148 vs. 112 hours of aerobic stability). The use of OA increased the soluble fraction (a), the potentially degradable fraction (b), and the effective degradability (ED) (P<0.01), and reduced the undegradable fraction (U) in intermediate- (268 vs. 287 g kg-1 DM) and late-maturity (245 vs. 322 g kg-1 DM) silages. In general, organic acids effectively mitigated aerobic deterioration and promoted DM digestibility in corn silage with a DM content above 350 g kg-1. *Autor for correspondence

The objective of this research work was to assess the effect that cutting time and moisture content at baling have on losses in production process and nutritional quality when it comes to the storage of Paiaguas grass hay. The assessed treatments were hay harvested at 10:00, 13:00 and 16:00, and baled at two moisture levels, 15% and 20%. The lowest dry matter losses were recorded when cutting happened at 10:00, and with baling at 15% moisture. Non-fibrous carbohydrate content increased for the cut made in the afternoon, and reduced during the storage period, with an influence for cutting time and baling moisture. There was an increase in fibrous fraction content in all assessed treatments with storage time, especially for the material that was baled at a 20% moisture. During storage, dry matter digestibility reduced mainly in hay stored at a 20% moisture, harvested at 10:00 and 13:00. The best time to cut forage for haymaking is in the afternoon, between 13:00 and 16:00.

This trial was designed to evaluate the effect of processing method of rehydrated corn grain silage (RCGS) on feed intake, performance, carcass traits, feeding behavior, rumen morphology, and blood metabolites of cattle in the finishing phase. Thirty-eight F1 Angus x Nellore bulls (365 +/- 22 kg) raised under grazing conditions were housed in individual pens (2 x 4 m) for the feeding trial. At the end of the adaptation period, animals were weighed after a 16-h fast, blocked by shrunk body weight, and randomly assigned to one of two dietary treatments: GRC, consisting of RCGS that was ground before ensiling using a hammer mill with a uniform 8-mm screen (1.52 mm geometric mean particle size); and RRC, consisting of RCGS that was rolled before ensiling in a roller mill mounted in a bagging machine (2.18 mm geometric mean particle size). Diet ingredients were mixed manually twice daily, at 09:00 and 15:00 h, and offered as total mixed rations in amounts approximately 50 g/kg in excess of daily intake. The experimental diets contained a forage:concentrate ratio of 130:870 g/kg, with 644 g/kg of RCGS. The GRC resulted in greater daily variation in dry matter intake, total-tract digestibility (dry and organic matter), fecal pH, rumen papillae width, and lower first meal duration, meal length, fecal starch, and rumen papillae height than the RRC. However, grinding or rolling RCGS did not affect dry matter intake, growth performance, carcass traits, or health (liver abscesses, ruminitis, serum D-lactate) of finishing beef cattle. Therefore, the processing equipment to make RCGS might be preferable based on equipment availability, milling yield, energy consumption, and diet composition.

O objetivo do trabalho foi avaliar o efeito do horário de corte e do teor de umidade no enfardamento sobre as perdas no processo de produção e a qualidade nutricional na armazenagem do feno do capim Paiaguás. Os tratamentos avaliados foram, feno ceifado nos horários 10; 13 e 16 h e enfardado em dois teores de umidade, 15 e 20%. As menores perdas de matéria seca foram obtidas no corte às 10 horas e enfardamento com 15% de umidade. Os teores de carboidratos não fibrosos aumentaram para o corte realizado no período da tarde e reduziram durante o período de armazenamento, com influência para horário de corte e umidade de enfardamento. Houve aumento no teor da fração fibrosa em todos os tratamentos avaliados com o tempo de armazenamento, principalmente para o material que foi enfardamento com 20% de umidade. Durante a armazenagem a digestibilidade da matéria seca reduziu principalmente nos fenos armazenados com 20% de umidade ceifados às 10 e 13 h. O melhor horário de corte da forragem para fenação é no período da tarde entre 13 e 16 h.

ABSTRACT The objectives were to estimate the potential of S2 corn progenies for forage-related traits, and use of AMMI analysis to evaluate topcrosses compared to the classic analyzes. Progenies were crosses with four different testers: LG 6030, 2B688, 9.H3.33 and 53F.P37. Topcross hybrids were evaluated in four 9 x 9 simple square lattice design, during the 2017/18 season at Maringa, Parana State. Grain yield, forage fresh matter yield, and forage dry matter yield were measured. Classical approach was composed by variance components, general and specific combining ability, whereas AMMI analysis was performed for progenies x testers interaction, considering additive main effects and multiplicative effects. Considering the classical approach, testers LG 6030 and 2B688 better expressed the genetic variability between progenies for grain yield. AMMI analysis allowed the partitioning of the sum of squares in additive main effects and multiplicative effects, being a complementary result for the classical approach. Progeny 14 was selected due to higher general combining ability for grain yield, forage fresh matter and forage dry matter yield. Topcrosses 14x9.H3.33 and 14x2B688 were selected due to their higher specific combining ability, additive and multiplicative effects. The AMMI analysis was effective and helped in the interpretation of the results.

Grass ensilability varies with maturity stage, mainly due to changing concentrations of dry matter and soluble carbohydrates with progressing forage maturity. Consequently, the required dose of silage additive to prevent the development of undesirable microorganisms may change with maturity stage. The objective of this study was to verify whether the application rate of an ad-ditive containing sodium nitrite and hexamine interacts with guinea grass maturity to alter silage fermentation and chemical composition. Four fields of guinea grass (0.5-0.7 ha each field) were mowed and divided into two plots per field. After 5 wk, one plot of each field was mowed again to establish differences in stage of maturity. Ten weeks after the first mowing, the grass plots with 5 -and 10-wk regrowth were manually harvested and used for the trial. The grass from each plot (approx. 30 kg) was chopped and divided into 3 piles, totaling to 24 piles, as result of four fields, two maturities, and three additive treatments: control (without additive), low dose of sodium nitrite (0.5 g/kg) + hexamine (0.325 g/kg) (NHL), and high dose of sodium nitrite (1 g/kg) + hexamine (0.65 g/kg) (NHH). After 90 d of storage, the silos were opened and silages sampled to determine dry matter (DM) loss, microbial counts, fermentation end-products, aerobic stability, chemical composition, and in vitro DM digestibility. Guinea grass harvested at 10-wk regrowth had a lower content of crude protein (P < 0.001) and a greater content of cell wall components (P < 0.001), resulting in a more lignified (P < 0.001) and less digestible (P < 0.001) forage than that harvested at 5 wk. There were interactions between plant maturity and additive dose for several silage traits (P < 0.05), likely due to the slightly greater fermentability coefficient (+5.1 points) for the more mature grass (P < 0.001). Within each maturity stage, silage pH and fermentation end-products associated with clostridia metabolism (i.e., n-butyric acid, propionic acid, i-butyric acid, i-valeric acid, n-valeric acid, ammonia, and 2,3-butanediol) linearly decreased (P < 0.001) with additive application rate, but the magnitude of improvement was slightly greater for 5-wk than 10-wk regrowth. Application of additive linearly decreased silage DM loss at both 5-wk (95.2, 46.7, and 20.6 g/kg DM, P < 0.001) and 10-wk (66.5, 31.7, and 13.6 g/kg DM, P < 0.001) regrowth stages, but only silages treated with NHH had n-butyric acid concentration < 3 g/kg DM. The proportion of rumen undegradable protein (P < 0.001), soluble carbohydrates concentration (P < 0.001), and in vitro DM digestibility (P < 0.001) were linearly increased with additive dose within each maturity stage. As treated silages were better conserved, silage aerobic stability was linearly reduced (P < 0.001) with additive dose, although all silages were aerobi-cally stable for >= 4.7 d. In conclusion, the additive based on sodium nitrite and hexamine, applied at a regular dose, was able to largely restrict Clostridium development and DM losses during fermentation of guinea grass silage at both maturity stages. However, harvesting more mature grass markedly impaired its chemical composition and digestibility, rendering it no feasible strategy to reduce the additive application rate by half.

Resumo Objetivou-se avaliar os efeitos de differentes estratégias de vedação sobre a estabilidade aeróbia e o valor alimentício da silagem de milho fornecida para cordeiros em terminação. Os tratamentos foram definidos de acordo com a estratégia de vedação do silo: LP (lona preta de polietileno), LP + Bagaço (lona preta de polietileno + bagaço de cana) e LP + Silostop (lona preta de polietileno + filme de barreira de oxigênio Silostop® Orange). Foram utilizados seis cordeiros por tratamento, totalizando 18 animais, em um período experimental de 63 dias. A silagem do tratamento LP apresentou maior estabilidade aeróbia, porém proporcionou menor coeficiente de digestibilidade da matéria seca. Não foi observada diferença significativa entre os tratamentos para o consumo e desempenho dos cordeiros. Todavia, para o peso corporal final, ganho de peso, ganho médio diário, eficiência alimentar e consumo de matéria seca, os melhores resultados, em valor absoluto, foram encontrados para os cordeiros alimentados com dieta à base da silagem coberta com LP + Bagaço. A silagem vedada exclusivamente com a lona preta de polietileno apresentou maior estabilidade aeróbia. As diferentes estratégias de vedação utilizadas nesse experimento não influenciaram o desempenho de cordeiros Dorper x Santa Inês em terminação.

Abstract The objective of this study was to evaluate the effects of different sealing strategies on aerobic stability and feed value of corn silage supplied to finishing lambs. The treatments were set up according to the silo sealing strategy: BP (black polyethylene film), BP + Bagasse (black polyethylene film + sugarcane bagasse) and BP + Silostop (Silostop® Orange oxygen barrier film + black polyethylene film). Six lambs per treatment were used, totaling 18 animals in an experimental period of 63 days. The silage from LP treatment presented the highest aerobic stability, however with lower dry matter digestibility coefficients. No significant differences were detected among treatments for intake and performance of lambs. But for final body weight, weight gain, daily average gain, feed efficiency and dry matter intake, the best results, in absolute value, were found for lambs fed with silage from LP + Bagasse treatment. The silage sealed exclusively with black polyethylene film showed greater aerobic stability. The different sealing strategies used in this experiment did not influence the performance of finishing Dorper x Santa Inês lambs.

The objective of this study was to assess the effect of cutting time on the nutritional composition and dehydration rate of stargrass, as well as the nutritional value of the hay as a function of storage time. Two plant cutting times were analyzed: at 13:00 (H13) and 17:00 (H17). After cutting, the dehydration rate of both the plant and its fractions until baling was monitored. The bales were checked for nutritional composition and digestibility after 30, 60, 90 and 120 days. At the time of cutting, a difference was observed for the concentrations of ethanol-soluble carbohydrates, which were higher for H17 (90.3 g kg-1) compared to H13 (52.9 g kg-1). Leaf dehydration rates were higher in the H17 treatment. Cutting time had no influence on the nutritional value of the hay. With storage time, there was an increase in the levels of neutral detergent fiber and acid detergent fiber, and a reduction in the content of ethanol-soluble carbohydrates. It was concluded that cutting at 17:00 allows for a greater accumulation of soluble carbohydrates in the plant. Cutting time does not change the time required for dehydration and the nutritional value of the hay. Storage time reduces soluble components and increases fibrous constituents

ABSTRACT We investigated the effects of corn grain, finely or coarsely ground, rehydrated and ensiled to 35% moisture in substitution of dry corn grain on performance of beef cattle in the feedlot. Forty non-castrated young Angus crossbred bulls with average age of 13±1.4 months and average initial body weight (BW) of 374±14 kg. The experiment was conducted in blocks by weight, and bulls were randomly assigned into four groups of five animals each in a 2 × 2 factorial scheme. The factors evaluated were particle size (finely and coarsely ground) and two grain sources (dry ground corn and rehydrated corn grain silage). The treatments were diets containing dry corn grain, finely ground (DCF; 1.86 mm); dry corn grain, coarsely ground (DCC; 3.53 mm); rehydrated and ensiled corn grain, finely ground (RCF; 1.86 mm); and rehydrated and ensiled corn grain, coarsely ground (RCC; 3.53 mm). Initial BW, final BW, average daily gain (ADG), feed efficiency, and intake of dry matter (DMI), acid detergent fiber, and metabolizable energy were not affected by treatment. Ensiling corn grain decreased DMI by 10.3% (11.6 vs. 10.4 kg/d for dry and ensiled, respectively) and increased feed efficiency by 13.3% (0.13 vs. 0.15 kg/d for dry and ensiled, respectively), but there was no effect of particle size, grain source, and their interaction on ADG. Effects of particle size and grain source were observed for fecal starch and total tract starch digestion, with evidence that treatments containing rehydrated corn diets showed greater efficiency in the utilization of dietary starch. Animals fed RCF diets showed lower fecal starch losses of 37, 55, and 75% when compared with treatments RCC, DCF, and DCC, respectively. Our results suggested that ensiled rehydrated corn grain improves feed efficiency in substitution of dry corn grain. The finely and coarsely ground of rehydrated and ensiled corn grain increases the digestibility of starch for finishing cattle in feedlot.

We investigated whether the intercropping of maize and soybean could improve the silage nutritional content without reducing the forage yield or worsening silage fermentation process and aerobic stability. Three crop arrangements were studied: maize monoculture, soybean monoculture and maize-soybean intercropping. The experimental design was completely randomized with 5 replicates per treatment. Maize-soybean intercropping decreased the dry matter (DM) and grain yield as well as the production of digestible dry matter per hectare. The crude protein content of maize-soybean intercropped silage was higher compared with maize in monoculture (by 40%), but, on average, both silages presented similar fermentation profile, in vitro digestibility (600 g/kg DM), dry matter loss (37.1 g/kg DM), gas loss (36 g/kg DM) and aerobic stability (60 hr). Soybean-crop silage presented an elevated content of volatile organic compounds, low lactic acid concentration (2 g/kg DM), high pH (5.26), and greater losses of dry matter (73 g/kg DM) and gas (98.5 g/kg DM) during fermentation. Aerobic stability was higher in soybean-crop silage (192 hr) due to the high content of volatile fatty acids (butyric acid > 87 g/kg DM) and low contents of residual sugar and lactic acid. In conclusion, maize and soybean intercropping increased crude protein content, but contrary to our hypothesis, the crop association did not result in greater silage digestibility or higher aerobic stability, nonetheless reduced both crop productivity. Additionally, ensiling direct-cut soybean crop with low DM content is not recommended due to the high risk of undesirable fermentation and nutrient losses.

The objective of this study was to examine the effects of isopropanol alone or in combination with ethanol on performance, metabolism, and milk quality of dairy cows. Eight crossbred Jersey x Holstein cows (527 +/- 98 kg body weight; 152 +/- 44 days in milk) were allocated in two 4 x 4 balanced-Latin squares to receive one of four dietary treatments. Four cows were surgically adapted with rumen cannula. Diets contained 450 g/kg concentrates and 550 g/kg corn silage either added with (DM basis) 15 g/kg isopropanol, 15 g/kg ethanol, 15 g/kg isopropanol + 15 g/ kg ethanol, or water (control). Immediately before feeding, corn silage was sprayed with alcohols, mixed with concentrates, and fed as total mixed rations twice daily. Dry matter intake, total tract digestibility, ruminal fermentation pattern (pH, volatile fatty acids and NH3), urinary purine derivatives, milk yield, solids composition and oxidative capacity were not affected by treatments. However, gamma-glutamyl transferase activity increased (P < 0.01) in blood of cows supplemented with alcohols, indicating that isopropanol and ethanol were absorbed. Moreover, milk concentration of isopropanol and acetone increased (P < 0.01) in cows receiving isopropanol, but not ethanol. Consequently, milk from cows fed corn silage treated with isopropanol tested false-positive at the ethyl alcohol test in raw milk. In conclusion, dietary isopropanol and ethanol did not impair the performance of dairy cows, but isopropanol was imparted to milk and induced false-positive results at the ethyl alcohol test in raw milk.

Triticale high moisture grain triticale silage is an excellent option for ruminant diets, but loss control during its fermentation process should be further investigated. Thus, the objective of this study was to evaluate the effects of chemical and biological additives on high moisture triticale silages under chemical-bromatological composition, aerobic stability, and in vivo digestibility and ingestive behavior in sheep. The treatments were: high moisture triticale silage without additive (HMTC); high moisture triticale silage with enzyme-bacterial inoculant (HMTEB); high moisture triticale silage with 0.5 % urea in natural matter (HMTU); and high moisture triticale silage with 1.5 % sodium benzoate in natural matter (HMTSB). Four sheep were housed in appropriate metabolic cages according to the ethical principles of animal experimentation. The addition of urea as additive to high moisture triticale silage provided an increase in crude protein and ammoniacal silage (189.7 and 106.2 g kg MS-1, respectively) but did not affect digestibility (699.6 g kg MS-1 for HMTU, with a general average of treatments of 687.5 g kg MS-1) and ingestive behavior of sheep. Fiber consumption by sheep increased with the addition of the enzyme-bacterial additive in the silage (431.87 versus 388.06 g d(-1) of FDN for HMTEB and HMTC, respectively). All additives helped to preserve crude protein contents after silo opening, but none interfered in aerobic stability time of silage.

Silage is the main source of acetic acid in ruminant diets. In most silages, acetic acid is the fermentation product with the second highest concentration, after lactic acid. As it inhibits yeasts and therefore improves aerobic stability of silages, moderate concentrations of up to 30 g/kg dry matter (DM) are often recommended. However, acetic acid may impair the DM intake (DMI) by ruminants, most probably due to its sensory characteristics. The objective of this data-analysis was to evaluate the effect of the dietary content of acetic acid on the DMI in dairy cattle. Either rations containing silages inoculated with hetemfermentative Lactobacillus buchneri or rations treated with pure acetic acid were included in the dataset. Data analysis was performed with a mixed model, including random effects of experiment (intercept and slope) and fixed effects of acetic acid concentration (intercept, linear and quadratic terms). A broken-line regression showed the best goodness of fit (the lowest corrected Akaike's information criterion and the largest R-2 -adj = 0.77). Per 100 kg body weight (BW), an increase of 1 g acetic acid/kg DM led to a reduction of 1.2 g in DMI for acetic acid concentrations < 17.3 g/kg DM. From 17.3-60 g acetic acid/kg DM, DMI reduction was 5.6 g for each additional g of acetic acid in DM (per 100 kg BW). Therefore, dairy nutritionists should consider the content of acetic acid in fermented ingredients upon balancing the diet, to avoid DMI depression (< 17 g/kg DM). Considering typical proportions of silage in diet, current recommendations for the upper limit of acetic acid in silages might, from the perspective of maximizing DMI, be too high and therefore warranting reconsideration.

ABSTRACT: The use of intercropped grass legumes provides a source of sustainable animal production as these vegetables contribute to an increase in forage yield by area, and substitute inorganic nitrogen and other components. The objective of this study was to evaluate the nutritional characteristics of silages and the yield and milk quality of Holstein cows fed triticale silages in monoculture or intercropped with either oats or legumes. The crops for silage production were triticale (TS), triticale in consortium with forage pea (TSP), and triticale in consortium with oats, forage peas and vetches (TSOPV). The silages showed no differences in dry matter content. The highest crude protein (13.06 %) and ethereal extract content was observed in TSOPV, but in the case of the latter, there was little difference when compared with TS (2.35 and 2.16 %, respectively) although the ash contents of the TSOPV and TSP silages did present a difference compared to TS silage. The neutral and acid detergent fibers (NDF and ADF) and cellulose fractions of TS silage were higher (68.60, 41.46 and 38.19 %, respectively) than those in TSOPV and TSP silages, which also had higher levels of soluble nitrogen, ethanol and acetic acid. Dry matter intake was higher in both TSOPV and TSP, which also provided a higher milk yield (21.19 and 20.45 L cow d−1) compared to that of TS silage (18.74 L cow d−1). Cows fed TS also produced milk with a lower N-ureic content (15.15 mg dL−1). The inclusion of legumes with triticale provided good fermentative quality for silage and increased milk production of cows without altering their concentrations of fat and protein.

BACKGROUND The effect of live yeast Saccharomyces cerevisiae strain CNCM I-1077 (SC) on the ruminal degradability of different forages commonly found in dairy diets in South America was evaluated. We also assessed if SC supplementation interacts with forage group to affect ruminal fiber degradability. Four non-lactating rumen-cannulated Holstein cows were randomly assigned to two treatment sequences: Control-SC-Control or SC-Control-SC, in a switchback design, with three 30-day periods. Cows in the SC treatment were supplied with 1 x 10(10) colony-forming units of yeast daily via rumen cannula. In situ degradability of dry matter (DM) and neutral detergent fiber (aNDF) was measured in 15 forages collected in South America. Forages were assigned to one of three groups: corn silages; tropical grasses (sugarcane silages and tropical grass silages); and temperate grasses and alfalfa (oat silages, ryegrass silages, alfalfa silage, and alfalfa hay). RESULTS Cows supplemented with SC had higher (P = 0.05) counts of yeasts and lower (P = 0.03) concentration of lactate in rumen fluid. There was no interaction between forage group and yeast supplementation (P > 0.10) on in situ degradability. The SC increased DM (by 4.6%) and aNDF degradation (by 10.3%) at 24 h of incubation (P < 0.05). Metabolomics revealed that a chemical entity (C17H29N6O3, m/z 365.2284 [M + H](+)) from the family of lipids and related molecules was suppressed in the rumen fluid of cows supplemented with SC. CONCLUSION The SC supplementation improved DM and aNDF degradability regardless of the forage group. (c) 2021 Society of Chemical Industry.

Our objective was to determine the effects of two strains of obligate heterofermentative bacteria, alone or in combination, on the fermentation profile, gas production kinetics, chemical composition, and aerobic stability of sugarcane silage. A plot of sugarcane was manually harvested, mechanically chopped and treated with: distilled water (5 mL kg –1 ; Control), Lentilactobacillus hilgardii CNCM I-4785 [3 × 10 5 colony-forming units (cfu) g –1 ; LH], Lentilactobacillus buchneri NCIMB 40788 (3 × 10 5 cfu g –1 ; LB), and LH+LB (1.5 × 10 5 cfu g –1 of each strain). Treated forages were packed into 1.96-L gas-tight silos (0.40 porosity) and stored at 25 ± 1.5°C for 70 days (4 replicates per treatment). All heterolactic inoculants were effective to increase acetic acid concentration and inhibit yeast metabolism, as treated silages had lower formation of ethanol, ethyl esters and gas during fermentation. Lower fungal development spared soluble carbohydrates, consequently resulting in silages with higher in vitro digestibility. Nevertheless, L. buchneri was the most effective strain to extend the aerobic stability of sugarcane silage (based on both temperature and pH rise). The use of L. buchneri alone or in combination with L. hilgardii , applied at 3 × 10 5 cfu g –1 , is a feasible strategy to inhibit yeast metabolism and increase the nutritional quality of sugarcane silage.

Our objective was to compare the performance of dairy heifers fed diets based on whole-plant corn silage stored in bunker silos sealed with either standard polyethylene film (white-on-black, actual thickness 121 ± 3.1 µm) covering the top surface, held in place with rows of tires every 3 m (PE) or an oxygen barrier system comprised of an ethylene-vinyl alcohol film (actual thickness 46.7 ± 2.5 µm) lining side walls and covering the silage, protected with a woven anti-UV cover and gravel bags placed around the edges and every 3 m across the silo (OB). Whole-plant corn was mechanically harvested at 39% dry matter (DM), packed in bunker silos, and sealed with PE or OB covering methods. After 6 mo of storage, silos were opened and fed to 26 Holstein heifers (260 ± 89.1 kg of shrunk body weight) for 60 d. Heifers were blocked by initial weight (13 blocks with 2 heifers each block) and housed in individual pens. Diets contained (on a DM basis) 80% corn silage (PE or OB), 17.5% soybean meal, and 2.5% mineral mix. Dry matter intake was measured daily, whereas shrunk body weight, hip height, heart girth, and body condition score were measured at the beginning and end of the experiment. Feeding behavior was recorded on d 24 and 46, and total-tract digestibility was measured from d 26 to 30 and 48 to 52. Data of intake, feeding behavior, and digestibility were averaged by animal for the whole feeding period before the statistical analysis. Data of animal performance were analyzed as a randomized complete block design. Initial shrunk body weight was used as a covariate for analyses of intake and body measures. During feed-out, silage quality was also assessed at the top (15 cm depth from upper surface) and bottom layer (135 cm depth from upper surface) and analyzed as a split-plot design. Silage stored under the OB sealing system had less yeast, mold, and NH3-N, and more lactic acid and ethanol-soluble carbohydrates. An interaction between sealing strategy and silo layer showed that OB silage had lower values of temperature, pH, anaerobic spores, acetic acid, and DM loss, and greater in vitro DM digestibility and aerobic stability, especially in the top layer. The proportion of inedible silage was lower in OB than in PE treatment (0.82 vs. 4.00% DM). Total-tract digestibility was similar between treatments, but animals that received the OB diet had higher DM intake by approximately 9% (9.39 vs. 10.20 kg/d) due to a faster eating rate and a greater number of meals per day. Therefore, OB treatment increased the digestible energy intake by 8% (26.3 vs. 28.3 Mcal/d) and average daily gain by 12% (1.08 vs. 1.21 kg/d). Body condition score change was similar between treatments, but heifers fed OB had greater heart girth and tended to have higher hip height. In conclusion, replacing a standard PE film with an OB sealing system improved silage conservation and performance of growing dairy heifers.